Onion Omega2 - I2C OLED Bouncing Dot using C

bouncing_dot.c

/**
 * A small demo of a dot bouncing inside a 128x64 OLED screen, using the Onion Omega 2. Note this isn't using the
 * OLED expansion, but a cheapo screen I bought from China, using the SSD1306 (as far as I could tell) driver.
 * This was only a personal exercise to see how easy it is to setup, it might be handly to someone else learning!
 *
 * To compile:
 *    - install gcc and make (See: https://docs.onion.io/omega2-docs/c-compiler-on-omega.html)
 *    - install git (Follow this: https://docs.onion.io/omega2-docs/installing-and-using-git.html)
 *    - install python-dev
 *    - git clone the i2c exp driver (https://github.com/OnionIoT/i2c-exp-driver)
 *    - (At the time of writing) Alter the makefile according to this bug report (https://github.com/OnionIoT/i2c-exp-driver/issues/18)
 *    - go into the "i2c-exp-driver" project and compile with `make`
 *    - copy bin, include, lib directories to /usr
 *    - compile gist below with `gcc bouncing_dot.c -loniondebug -lonioni2c -lonionoledexp`
 *    - Run!
 *
 * @author Adam Buckley <[email protected]>
 */
// #include <stdio.h>
#include <unistd.h>
#include <oled-exp.h>

int main() {

  // Init the OLED
  int status  = oledDriverInit();
  status |= oledSetDisplayPower(1);
  
  int x = 0, y = 0;
  int delta_x = 1, delta_y = 1;

  // Run forever
  while(1) {
    x += delta_x;
    y += delta_y;

    // When X hits a boundary on the OLED, flip the delta position
    if (x == 0 || x == 63) {
      delta_x *= -1;
    }

    // Do the same for the y coordinate
    if (y == 0 || y == 127) {
      delta_y *= -1;
    }
  
    // Set cursor to correct position
    // The way this works is that while the height of the OLED is 64px, there
    // is 8 logical rows, each with 8 addressable pixels. So the code below is just
    // working out where a pixel (e.g x = 57) should be placed
    
    // See https://docs.onion.io/omega2-docs/oled-expansion-c-library.html#understanding-the-display-1 for more info
    status |= oledSetCursorByPixel(((int) x / 8), y);
    switch(x % 8) {
      case 0:
        status |= oledWriteByte(0x01);
        break;
      case 1:
        status |= oledWriteByte(0x02);
        break;
      case 2:
        status |= oledWriteByte(0x04);
        break;
      case 3:
        status |= oledWriteByte(0x08);
        break;
      case 4:
        status |= oledWriteByte(0x10);
        break;
      case 5:
        status |= oledWriteByte(0x20);
        break;
      case 6:
        status |= oledWriteByte(0x40);
        break;
      case 7:
        status |= oledWriteByte(0x80);
        break;
    }
                
    // A larger usleep value will make the dot move slower
    usleep(10000);
          
    // Clear the current dot on the screen
    status |= oledSetCursorByPixel(((int) x / 8), y);
    status |= oledWriteByte(0x00);
    
    // Clear below for some reason will cause the screen to not print anything
    // status |= oledClear();
  }

  return 0;
}

Thanks for the very clear compilation instructions.

However, I just noticed that the OLED Expansion Python Module commands to setCursor stopped working after I followed your compilation steps (gcc, make, git, python-dev installs).

In a Python shell, the OLED command "oledExp.setCursor(0,0)" (for example) now returns: "IOError: I2C transaction failed." Same for setCursorByPixel(...)." I tried the Sierpinski triangle example in the i2c-exp-driver Github repo, and it fails as well, at the same point. Other commands still work (driverInit, clear, write, wWriteByte, etc.).

Any ideas?